compel/test: Makefiles cleanup

1. Remove COMMON_IDIR -- there's no need for it, and it makes
   the build process look more complicated than it is.

2. Use standard CC and CFLAGS defines (so one can use say make CC=clang)

3. Drop the dependency on COMPEL_LIBRARY, as it's supposed to be
   an external file/tool.

4. Add -Wall to CFLAGS.

5. Simplify ARCH setting in infect test.

6. Drop ARCH from rsys test, as it's not used there.

travis-ci: success for More polishing for compel cli
Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>